delivery semantics?

[Victor L <vl...@gmail.com>]

Can someone clarify it:
- "At most once": messages may be lost but are never redelivered
Does it mean: "commit, when message is received by leader partition,
retries disabled for producer no matter of ISR status"?
- "At least once": commit only when message is ackd by all partitions in
replication set, if not - keep retrying by producer"?

- "Exactly once - each message is delivered only once"... What does that
mean? Delivered to leader partition and never replicated?

Thank you,
V

Re: delivery semantics?

[Jacob Sheck <sh...@gmail.com>]

Your question seems to be confusing the producer and consumer
responsibilities in message delivery durability.  Neha from Confluent wrote
a blog post about this which should help your understanding of the how the
Kafka clients handle this.

https://www.confluent.io/blog/exactly-once-semantics-are-possible-heres-how-apache-kafka-does-it/

There is a clear description in the section titled "Overview of messaging
system semantics."

On Fri, Mar 30, 2018 at 10:03 AM Victor L <vl...@gmail.com> wrote:

> Can someone clarify it:
> - "At most once": messages may be lost but are never redelivered
> Does it mean: "commit, when message is received by leader partition,
> retries disabled for producer no matter of ISR status"?
> - "At least once": commit only when message is ackd by all partitions in
> replication set, if not - keep retrying by producer"?
>
> - "Exactly once - each message is delivered only once"... What does that
> mean? Delivered to leader partition and never replicated?
>
> Thank you,
> V
>